Here is a compelling reason not use pie charts when visualizing data:

One of your stakeholders has an MBA and has read exactly one book on data visualization (you know which one). He thinks pie charts are oh so terrible, and if your reports and dashboards contain pie charts, instead of focusing on the data being communicated, he will complain about the pie charts. Because your goal as somebody making charts is to faciliate understanding, avoiding pie charts altogether can actually be a smart strategy. For all their merits, you never scrictly "need" pies (or any one chart type). If chart's form would be a distraction from the data, it is maybe not the the right chart.

Fuck that guy.